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Areas of the lower 48 states in exceptional drought declined for the sixth straight week, while areas in other categories of drought contracted slightly on the August 13 U.S. Drought Monitor map.

“Rain in some of the nation’s driest areas, including the central and southern High Plains and the Southwest, has led to a sharp decrease in the coverage of exceptional drought (D4),” observed Brad Rippey, a meteorologist in the U.S. Department of Agriculture’s Office of the Chief Economist. “On August 13, D4 covered just 2.03 percent of the continental U.S., down nearly three-quarters of a percentage point from a week ago to the lowest value since July 17, 2012.”

The total area of the country in drought receded fractionally in the past week, with 45.26 percent of the lower 48 states now in moderate drought or worse, compared with 45.49 percent a week earlier. Areas improving included parts of Arkansas, Texas, Oklahoma, Kansas, Nebraska, South Dakota, New Mexico and Colorado. Drought spread or intensified in eastern Texas, Louisiana, the southwest corner of Arkansas, Iowa, Idaho, Hawaii, Alaska and California.

“Resurgent drought in the western Corn Belt has left moderate drought (D1) covering 35 percent of Iowa and 15 percent of Missouri,” Rippey said. “The portion of the U.S. corn production area in drought has been edging upward in recent weeks, from 17 to 24 percent between July 9 and August 13. The increase has been largely due to the return of drought to parts of the western Corn Belt, including northern Missouri, eastern Nebraska, and Iowa. Soybeans in drought have also increased in the last five weeks, from 8 to 16 percent. Hay (33 percent) and cattle in drought (46 percent) were both down one percentage point from last week, on the strength of heavy rain in Kansas, Oklahoma, and the mid-South.”

To the west, a patch of extreme drought covering 11.36 percent of California emerged on this week’s map, the largest amount of extreme drought in that state since February 2009.

The map’s author, Mike Brewer, said in accompanying narrative that California is in its second year of below-normal rainfall and this year is its driest January to July on record.

It should be noted that California’s highly managed water delivery system protects urban and many agricultural water users from most effects of short-term droughts. The U.S. Drought Monitor map is based on analysis of moisture deficiencies over time and on reported impacts. In areas with highly managed water supplies, even fairly serious short-term drought conditions may not result in many impacts.

“Obviously, drought is complicated in highly managed regions and the Drought Monitor’s primary aim to date hasn’t been about the managed systems that are concerned with irrigation and urban water supplies,” said Mark Svoboda, who leads the National Drought Mitigation Center’s Monitoring program area and is one of the original U.S. Drought Monitor authors. “It’s about the unmanaged systems where irrigation isn’t necessarily in play.”

Impacts are more likely to show up in areas other than urban water supply and irrigated agriculture, such as rural communities’ water supplies, rangeland conditions, wildfire, and wildlife habitat.

For example, near Frazier Park, Calif., a rancher was curtailing operations due to lack of grass, and people in Lake of the Woods, an unincorporated area in Kern County, were restricted from watering gardens, according to a citizen science observation submitted to the Drought Impact Reporter on June 22. (http://moderator.droughtreporter.unl.edu/RSSfeed/ImpactView/29091)

Kings River is very low this year, according to local officials quoted in the Hanford Sentinel on July 30 (“Kings high and dry with nowhere to go”). The story said the river was barely deep enough to wade in earlier in the year, when the river normally supports floating, and had completely stopped flowing by late July. While some parts of the river still had pools where people could swim, others had tire tracks from illegal off-roading. The Kings River watermaster told the paper this is the seventh-driest year on record in 115 years of record-keeping. (http://moderator.droughtreporter.unl.edu/RSSfeed/ImpactView/29377)

Also, California’s wildfire season was off to an early and active start. According to the California Department of Forestry and Fire Protection, 4,514 fires had burned 92,353 acres from the start of 2013 through Aug. 10, in contrast with 3,260 fires burning 42,916 acres last year for the same period, and in contrast with an average from 2008 through 2012 of 3,164 fires burning 114,339 acres during the same time of year. The five-year average for acres burned is skewed on the high side because it includes 2008, which was the year with the most acres burned in California history, according to CAL FIRE spokesman Daniel Berlant.

U.S. Drought Monitor authors synthesize many drought indicators into a single map that identifies areas of the country that are abnormally dry (D0), in moderate drought (D1), in severe drought (D2), extreme drought (D3) and exceptional drought (D4). The map is released each Thursday based on data through the previous Tuesday morning.

The U.S. Drought Monitor map is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the National Oceanic and Atmospheric Administration, the USDA, and about 350 drought observers across the country. Brewer is with NOAA’s National Climatic Data Center.